Spray nozzles are critical pieces of equipment for jet ejector venturi (JEV) wet gas scrubbers (WGS), which service various refinery components, including high value fluid catalytic cracking (FCC) units. The nozzles are designed to co-currently spray a scrubbing liquid into a chamber containing a hot, turbulent gaseous stream, e.g. FCC flue gas. The gaseous stream may contain certain contaminants including sulfur oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO2) as well as dispersed particulate matter. These contaminants are must be removed under strict regulatory guidelines.
The nozzles generate a high pressure spray which is well-mixed with the flue gas to minimize the contaminants escaping into the atmosphere and also provide enough vacuum to propel the flue gas through the scrubber. Conventional nozzles used in these applications comprise at least two separate pieces, a nozzle assembly and a vane assembly. The nozzle assembly can be made of hardened stainless steel, but is typically comprised of a steel nozzle lined with ceramic. The vane assembly is generally made of hardened stainless steel and is ground-to-fit within a cylindrical portion of the ceramic-lined nozzle assembly.
Hardened stainless steel is more susceptible to corrosion and erosion than ceramic. As such, vanes of conventional vane assemblies over time will exhibit signs of corrosion and/or erosion and will need to be removed from service. In other instances, the vane assembly can be subjected to over-grinding before installation within the cylindrical portion of the ceramic nozzle assembly. Over-grinding can permit movement between the vanes and the cylindrical portion of the ceramic nozzle assembly, which can lead to the vane assembly spinning when the scrubbing liquid impacts the vanes. This spinning can result in catastrophic failure of the nozzle, which can require shut down of surrounding equipment at significant expense.
Replacing a hardened stainless steel vane assembly with a ceramic vane assembly does not fix the above problems. The issues could be solved by eliminating the joint between the vane and nozzle assembly. Thus, it would be advantageous to produce a nozzle assembly, with incorporated vane assembly, that consisted of a single piece of ceramic.